我々 は我々 の在籍を認める、エコール連邦工科ローザンヌ (EPFL) の寛大なサポートのため。このプロジェクトは、欧州連合のホライゾン 2020年研究所から資金を受けているし、イノベーション プログラム マリー ・ スクウォドフスカ = キュリーの下で許諾契約番号 665667。著者は、x 線回折でご支援パスカル アレキサンダー Schouwink をありがとうございます。

注意: 読み慎重に関与する化学物質の化学物質安全性データ シート (MSDS) です。実験で使用される化学物質の一部が有毒です。本手法は、ナノ粒子の合成を含まれます。したがって、適切な予防措置を取る。全体の合成手順は、換気の発煙のフード実行する必要があります。
注: 器械、化学薬品、および MOF 膜の合成に関与する材料の詳細を表 1に示します。
1. 前駆体ゾルの金属塩溶液とリンカー ソリューションの準備
注: ZIF 8 フィルムの合成、金属塩として使用されて亜鉛硝酸 [Zn (3)2.6H2O]、2-methylimidazole (HmIm) は、リンカーとして使用されます。
<ol><li>金属塩溶液の Zn (3)2.6H2O の水の 500 mL の 2.75 g を溶かします。</li>
	<li>リンカー ソリューションの 56.75 g HmIm の 500 mL の水に溶かすし、透明な溶液が得られるまで継続的に攪拌します。</li>
</ol>2. Cu 電極の作製
<ol><li>4 × 4 cm 部分に (99.9% 純度、127 μ m 厚) の高純度銅箔をカットします。</li>
	<li>クランプ カット箔銅わに口クリップのセットを容易にするため 1 つの正方形の箔の端から 0.5 cm の距離で直線を描画します。</li>
	<li>円筒型ローラ ベアリングを使用してきれいな表面に箔を平らにします。</li>
	<li>15 分、15 分のイソプロパノールの風呂 sonication によって続いてのアセトン浴 sonication によって銅箔を徹底的に掃除します。</li>
	<li>クリーンな雰囲気で銅箔を乾燥させます。</li>
</ol>3. 基板の電極 (陰極) に添付ファイル
注: MOF フィルムに適切な基質を選んだ。AAO (Anodisc、0.1 μ m の細孔径と 13 mm 径ホスティング毛穴)、ポリアクリロニ トリルに応用できる (パン、分子量カットオフ: 100 kDa)、銅箔 (純度 99.9%、25 μ m 厚)、化学気相蒸着型のグラフェン フィルムで休んで、11銅箔と銅箔12,13,14日休んで自家製多孔質炭素膜。
<ol><li>慎重にテープを使用して銅の電極の中心に目的の基板を置きます。</li>
	<li>基板/電極アセンブリ水、イソプロパノール、続くと再び約 1 分のための水を洗い流してください。</li>
	<li>裸銅電極 (4 × 4 cm) をアノードに接続します。基板/電極アセンブリを陰極に添付しています。</li>
	<li>100 mL ガラス製ビーカーの内側 1 cm に 2 つの電極間の距離を調整します。</li>
</ol>4. ZIF 8 フィルムの手順を制定
<ol><li>31.6 g 金属前駆体溶液の 100 mL ビーカーにリガンド溶液の 35 g を混合し、30 の攪拌前駆体ゾルを形成する常温で s。 注: これらの条件で ZIF 8 の誘導時間は未満 60 s と、したがって、EPD が遅滞なく実施されます。</li>
	<li>前駆体ゾルを容器、電極をホストに転送します。</li>
	<li>電極に 3.5 cm マークまで両方の電極を浸します。 注: 実験の結果, 我々 は観察したそのソル老化の 3 分は多孔質基材は、回避する必要があります (この特定のケースで AAO) の毛穴に小さい ZIF 8 核の浸透につながる前に電界の適用。したがって、電界がオン、3 分後にのみ核が大きくやや。</li>
	<li>4 分の 1 V の電圧の蒸着 EPD を実行します。現在は、2.5 から 3.5 mA の範囲にする必要があります。</li>
	<li>EPD の最後に、ビーカーをゆっくりと下げます。新鮮な析出核と基板との密着性が弱い、細心の注意をする必要があります基板の処理中取られます。</li>
	<li>乾燥した基板をガラス顕微鏡スライドに転送します。場所で基板を保持するためにテープを使用します。</li>
	<li>結晶成長、31.6 g 金属塩溶液とリンカー ソリューション 100 mL ビーカーに 35 g を混ぜます。</li>
	<li>前駆体溶液に基板と一緒にガラス顕微鏡スライドを縦置きし、30 ° C で 10 h を行わないでください</li>
	<li>結晶成長の 10 h まで後、30 分の水で基板を洗浄し、クリーンな雰囲気で乾燥します。</li>
</ol>5、ZIF 7 フィルムの手順を制定
<ol><li>次の相違点と ZIF 8 フィルムを使用したものに同様の方法で AAO サポートに ZIF 7 フィルムを合成します。</li>
	<li>Zn (3) 0.82 g を混合後2·6H2O 30 mL にジメチルホルムアミド (DMF) と 30 mL のメタノール、3 分間のベンズイミダゾール 0.72 g 遂行 1 分の EPD。</li>
	<li>Zn (3)2·6H2O の 0.58 g、0.3 g のベンズイミダゾール系薬剤、110 ° C 4 h で DMF の 30 mL を含む前駆体ゾルの ZIF 7 核フィルムを浸すことによって、ありふれた ZIF 7 フィルムを合成します。</li>
	<li>ソリューションを冷却後 12 h 60 ° C で乾燥が続く、DMF でそれを浸すことによって ZIF-7/AAO 膜を洗浄します。</li>
</ol>6. 膜の作製と評価
<ol><li>
膜の作製
	<ol>
<li>シーリング材の準備のため徹底的に同じ割合で樹脂と硬化剤を混ぜるし、1 h の混合物を残します。</li>
		<li>中心に 5 φ の穴を 24 mm 幅のスチール ディスクに ZIF-8/サポート膜を配置します。</li>
		<li>最初に基板の端に沿ってエポキシを適用し、その後、センターで 5 mm 径の穴を除いて基板をカバーします。</li>
		<li>一晩乾燥してエポキシを許可します。</li>
		<li>実体顕微鏡を使用すると、既知の基準縮尺と膜をスキャンします。</li>
		<li>グラフィカル ソフトウェアを使用すると、スキャンした画像から膜の露出面積を計算します。</li>
	</ol>
</li>
	<li>
ガス透過試験 注: 実験で単一成分ガス透過試験を行った自家製透過セルに高温 Kallenbach テクニック。マスフロー コント ローラー (MKS) と透過設定で使用される質量分析計は、誤差 5% の範囲内で較正されました。マスフロー コント ローラー (MFC) は、フィードとスイープのガス流量に調整されます。Ar は、透過濃度のリアルタイム分析校正質量分析計 (MS) を透過ガスを貫くスイープ ガスとして使用されます。<ol>
<li>ステンレス製透過セル内膜とスチールのディスクを置きます。</li>
		<li>スチール ディスクの上下に上記のバイトン O リングを配置することによってリーク タイトなフィットを確保してネジを固定します。合成の際に、吸着水を削除するには、定常 H2パーミアンスを到達するまで H2フライトデモ雰囲気下で 130 ° C で膜を乾燥します。</li>
		<li>庫内設定を置き、温度を 130 ° C に設定</li>
		<li>フィードと掃引線、予熱を確認します。</li>
		<li>フィードと 30 mL/min にスイープ側のガス流量を設定します。</li>
		<li>それぞれのフィードと、未透過上のニードル バルブを調整することによってスイープ側と透過側に 0.1 MPa の圧力を維持します。</li>
		<li>定常状態が確立されると、パーミアンスを計算します。</li>
		<li>ゆっくりと 30 ° C に (約 2 時間) でオーブン冷めるし、定常状態が確立されると、再び値を記録します。</li>
	</ol>
</li>
</ol>

<ol>
	<li>Knebel, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defibrillation+of+soft+porous+metal-organic+frameworks+with+electric+fields.">Defibrillation of soft porous metal-organic frameworks with electric fields.</a> Science. 358, 347-351 (2017).</li><li>Brown, A. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interfacial+microfluidic+processing+of+metal-organic+framework+hollow+fiber+membranes.">Interfacial microfluidic processing of metal-organic framework hollow fiber membranes.</a> Science. 345, 72-75 (2014).</li><li>Dzubak, A. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ab+initio+carbon+capture+in+open-site+metal-organic+frameworks.">Ab initio carbon capture in open-site metal-organic frameworks.</a> Nature Chemistry. 4, 810-816 (2012).</li><li>Gascon, J., Kapteijn, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Metal-organic+framework+membranes-high+potential,+bright+future.">Metal-organic framework membranes-high potential, bright future.</a> Angewandte Chemie International Edition. 49, 1530-1532 (2010).</li><li>Liu, X., Wang, C., Wang, B., Li, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+Organic-Dehydration+Membranes+Prepared+from+Zirconium+Metal-Organic+Frameworks.">Novel Organic-Dehydration Membranes Prepared from Zirconium Metal-Organic Frameworks.</a> Advanced Functional Materials. 27, 1-6 (2017).</li><li>Zhang, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+selective+NH2-MIL-53(Al)+MOF+membranes+with+high+permeability.">Hydrogen selective NH2-MIL-53(Al) MOF membranes with high permeability.</a> Advanced Functional Materials. 22, 3583-3590 (2012).</li><li>Kwon, H. T., Jeong, H. -. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+synthesis+of+thin+zeolitic-imidazolate+framework+ZIF-8+membranes+exhibiting+exceptionally+high+propylene/propane+separation.">In situ synthesis of thin zeolitic-imidazolate framework ZIF-8 membranes exhibiting exceptionally high propylene/propane separation.</a> Journal of the American Chemical Society. 135, 10763-10768 (2013).</li><li>Hou, J., Sutrisna, P. D., Zhang, Y., Chen, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Formation+of+ultrathin,+continuous+metal-organic+framework+membranes+on+flexible+polymer+substrates.">Formation of ultrathin, continuous metal-organic framework membranes on flexible polymer substrates.</a> Angewandte Chemie International Edition. 55, 3947-3951 (2016).</li><li>Barankova, E., Tan, X., Villalobos, L. F., Litwiller, E., Peinemann, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+metal+chelating+porous+polymeric+support:+the+missing+link+for+a+defect-free+metal-organic+framework+composite+membrane.">A metal chelating porous polymeric support: the missing link for a defect-free metal-organic framework composite membrane.</a> Angewandte Chemie International Edition. 56, 2965-2968 (2017).</li><li>He, G., Dakhchoune, M., Zhao, J., Huang, S., Agrawal, K. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrophoretic+Nuclei+Assembly+for+Crystallization+of+High-Performance+Membranes+on+Unmodified+Supports.">Electrophoretic Nuclei Assembly for Crystallization of High-Performance Membranes on Unmodified Supports.</a> Advanced Functional Materials. , (2018).</li><li>Li, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-area+synthesis+of+high-quality+and+uniform+graphene+films+on+copper+foils.">Large-area synthesis of high-quality and uniform graphene films on copper foils.</a> Science. 324, 1312-1314 (2009).</li><li>Rodriguez, A. T., Li, X., Wang, J., Steen, W. A., Fan, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facile+synthesis+of+nanostructured+carbon+through+self-assembly+between+block+copolymers+and+carbohydrates.">Facile synthesis of nanostructured carbon through self-assembly between block copolymers and carbohydrates.</a> Advanced Functional Materials. 17, 2710-2716 (2007).</li><li>Huang, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-area+single-layer+graphene+membranes+by+crack-free+transfer+for+gas+mixture+separation.">Large-area single-layer graphene membranes by crack-free transfer for gas mixture separation.</a> Nature Communications. , (2018).</li><li>Agrawal, K. V., Dakachoune, M., Huang, S., He, G., Dudani, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Ultrahigh flux gas-selective nanoporous carbon membrane and manufacturing method thereof. , (2017).</li><li>Liu, J., W&#246;ll, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-supported+metal-organic+framework+thin+films:+fabrication+methods,+applications,+and+challenges.">Surface-supported metal-organic framework thin films: fabrication methods, applications, and challenges.</a> Chemical Society Reviews. 46, 5730-5770 (2017).</li></ol>

著者が明らかに何もありません。

既存方法15に関するイナクト メソッドの傑出した機能は、イナクト法は、多孔質と無孔基板の広い範囲の非常にありふれた、極薄の MOF 薄膜の合成をできることです。任意の基板の前処理は避け、MOF 薄膜の合成のため非常に簡単ですこのメソッドを作るします。EPD 装置は核膜の成膜に使用されるが、機器は電源、金属電極と非常にシンプルでアクセス可能であるビーカーの...

分子ふるい膜分子の分離で高エネルギー効率し、燃料 CO2キャプチャ、浄水、溶剤回収など1,2の全体的なコストを減らすことができます。Mof は、関与する isoreticular 合成化学と比較的簡単な結晶化3のための分子ふるい膜の合成のための材料の有望なクラスです。これまで、MOF ZIF 4、-7、-8、-9、-11、-67、-90 と-93、UiO 66、HKUST-1 とミル 53 されていると報告された4,5を含む、多様な結晶構造の膜で構成されます。これらの膜は多孔質支持体に高品質多結晶 MOF 薄膜の結晶化により合成されます。一般に、高分離選択性を得るためには、(ピンホール粒界欠陥など) 多結晶 MOF 膜の欠陥を減らすために必要です。厚膜を結晶化する欠陥を減らすために便利な方法です。以前報告のいくつかに驚くことではないが、MOF の膜は (5 μ m) 以上の非常に厚い。残念ながら、厚膜は、膜透過を制限する長い拡散パスに します。したがって、選択性を向上させるパーミアンスを犠牲にしました。このトレードオフを回避するためには、極薄結晶化する方法を開発することが不可欠だ (< 0.5 μ m 厚)、無欠陥 MOF 映画。
ZIF 8 は、最も集中的にその優れた化学的および熱安定性および結晶化学6,7のための膜の合成の MOF を勉強です。これまで報告された極薄の ZIF 8 膜界面化学や ZIF-8 の不均一核形成を支持するありふれた多結晶膜に不可欠な基になる多孔性の基板のトポロジを変更して実現しました。例えば、陳ら。(3-アミノプロピル) プタデカフルオロテトラヒドロデシルトリエトキシシラン変更 TiO2の 1 μ m 厚 ZIF 8 膜の合成を報告-コーティング poly(vinylidene fluoride) (PVDF) 中空繊維8。彼らは高の不均一核形成密度を観察し、表面化学、ナノ構造の同時変更に起因します。ペイネマン グループは、金属キレートの polythiosemicarbazide (PTSC) サポート9に極薄の ZIF 8 膜を報告しました。PTSC のこのユニークな金属キレートの機能は、ZIF 8、その後につながった高速 ZIF 8 膜の不均一核形成を促進、亜鉛イオンの結合をもたらした。一般に、高性能 MOF 膜の合成が容易基板化学とナノ構造のチューニングただし、これらのメソッドは、非常に複雑な通常 MOF MOF の他の魅力的な構造膜を合成するを再適用できません。
ここで、いくつかの結晶材料10のありふれた薄膜を形成に再適用することができますシンプルで汎用性の高い結晶化アプローチを使用して ZIF 8 映画非常にありふれた、極薄の合成を報告する.ZIF 8 と ZIF 7 薄膜作製プロセスを大幅に簡素化、あらゆる基板前処理無しの例を示します。ZIF 8 フィルム基板 (セラミック、高分子、金属、カーボン、グラフェン) の広い範囲で用意しています。アルミニウムの陽極酸化 (AAO) サポートの 500 nm 厚 ZIF 8 フィルムには、魅力的な分離性能が表示されます。8.3 x 10-6 mol m-2の-1 Pa-1と 7.3 (H2/CO2)、15.5 (2H2/N)、16.2 (H2/CH4)、2655 (H の魅力的な理想的な選択性の高い H2パーミアンス2/C3H8) を実現します。
上記の偉業を可能にする結晶化アプローチはイナクトです。イナクトの結晶の前駆体ゾルから直接基板に ZIF 8 核を預金します。アプローチは、誘導時間 (場合に核前駆体ゾルに表示時間) の直後に非常に短時間 (1 〜 4 分) の EPD を利用しています。電界の荷電の MOF 核への応用は応用の電界 (E)、(μ)、コロイドの電気泳動度と濃度の強さに比例して磁束の電極に向かってそれらを駆動します。方程式 1 および 2 に示すように、核 (Cn)。
<img alt="Equation 1" src="/files/ftp_upload/58301/58301eq1.jpg"> (関係式 1)
<img alt="Equation 2" src="/files/ftp_upload/58301/58301eq2.jpg"> (式 2)
ここは v = ドリフト速度 Ζ = 原子核のゼータ電位 Εo = 真空の誘電率 Εr = 誘電体定数と Η = 前駆体ゾルの粘度。
したがって、 Eとを決定する ζ) 溶液の pH を制御することにより核の充填密度を制御できます。最密充填核前駆体ゾルの後の成長は、非常にありふれた多結晶膜を取得する研究者をことができます。

<table>
	<tbody>
		<tr>
			<td>Zinc nitrate hexahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>96482-500G</td>
			<td>98% purity</td>
		</tr>
		<tr>
			<td>2-Methylimidazole</td>
			<td>Sigma-Aldrich</td>
			<td>M50850-500G</td>
			<td>99% purity</td>
		</tr>
		<tr>
			<td>Benzimidazole</td>
			<td>TCI</td>
			<td>B0054-500G</td>
			<td>98% purity</td>
		</tr>
		<tr>
			<td>Tape</td>
			<td>DuPont</td>
			<td>KPT-1/8</td>
			<td></td>
		</tr>
		<tr>
			<td>Epoxy</td>
			<td>GC Electronics</td>
			<td>19-823</td>
			<td></td>
		</tr>
		<tr>
			<td>Copper foil</td>
			<td>Alfa Aesar</td>
			<td>13380.CV</td>
			<td>99.9% purity</td>
		</tr>
		<tr>
			<td>Power source for EPD</td>
			<td>Gamry Instruments</td>
			<td>Interface 1000E Potentiostat</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner</td>
			<td>MTI corporation</td>
			<td>VGT-1860QTD</td>
			<td></td>
		</tr>
		<tr>
			<td>AAO</td>
			<td>GE Healthcare Life Sciences&#8206;</td>
			<td>6809-7013</td>
			<td></td>
		</tr>
		<tr>
			<td>PAN</td>
			<td>Shandong MegaVision</td>
			<td></td>
			<td>The molecular weight cut-off is 100 kDa</td>
		</tr>
	</tbody>
</table>

electrophoretic crystallization of ultrathin high-performance metal-organic framework membranes

(高分子、セラミックス、金属、カーボン、グラフェン) そのまま多孔性および非多孔性のサポートの広い範囲に薄く、非常にありふれた多結晶金属有機性フレームワーク (MOF) 膜の合成を報告する.我々 はイナクト アプローチと呼ばれる新規結晶化技術を開発: 非常にありふれた薄膜 (イナクト) の結晶化の電気泳動核アセンブリ。このアプローチは、選択された基板を介して前駆体ゾルから直接電気泳動法 (EPD) Mof の不均一核形成密度の高いことができます。十分に詰めて MOF 核の成長は、非常にありふれた多結晶 MOF 映画に します。薄い、ありふれたゼオライト イミダゾール フレームワーク (ZIF)-7 と ZIF 8 フィルムの合成にこの単純なアプローチを使用ことができることを示す.結果 500 nm 厚の ZIF 8 膜示しかなり高い H2パーミアンス (10-6 mol m-2の-1 Pa-1x 8.3) 理想気体の選択性 (H2/CO2H2/N215.5 の 7.3H2/CH4と H2/C3H82655 の 16.2)。C3H6/C3H8分離のための魅力的なパフォーマンスが達成 (、C3H6透過 10-8 mol m-2の-1 Pa-1および C3H x 9.96/C3H8理想的な性 31.6 25 ° C で)。全体的にみて、そのシンプルさのおかげで、イナクト プロセスをナノポーラス結晶材料の広い範囲のありふれた薄膜を合成する拡張できます。

自家製 EPD セットアップは、MOF フィルム (図 1) を合成に使用されました。走査電子顕微鏡 (SEM) 像と x 線回折 (XRD) パターンは、ZIF 8 核フィルム (図 2) で収集されました。SEM は、AAO サポート、ZIF-8/AAO 膜、パン サポート、ZIF-8/PAN 膜、ZIF-8/グラフェン フィルムおよび ZIF-7/AAO 膜 (図 3) の表面および断面の...

Watch this Scientific Journal Video about Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes at JoVE.com

Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

極薄高性能金属有機性フレームワーク膜の電気泳動の結晶化

多孔質未変更の広い範囲でありふれた、多結晶金属有機性フレームワーク膜の合成のため、再現性のある、シンプルで多彩なアプローチと非多孔質金属支持が表示されます。

We report the synthesis of thin, highly intergrown, polycrystalline metal-organic framework (MOF) membranes on a wide range of unmodified porous and ...

electrophoretic-crystallization-ultrathin-high-performance-metal

Research

JoVE Journal

Chemistry

9.9K ビュー.  École Polytechnique Fédérale de Lausanne (EPFL). 多孔質未変更の広い範囲でありふれた、多結晶金属有機性フレームワーク膜の合成のため、再現性のある、シンプルで多彩なアプローチと非多孔質金属支持が表示されます。

ビデオ: Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes

Preparation of Hydrophobic Metal-Organic Frameworks via Plasma Enhanced Chemical Vapor Deposition of Perfluoroalkanes for the Removal of Ammonia

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high surface area microporous materials, such as metal-organic frameworks (MOFs), unique challenges present themselves for PECVD treatments. Herein the protocol for development of a MOF that was previously unstable to humid conditions is presented. The protocol describes the synthesis of Cu-BTC (also known as HKUST-1), the treatment of Cu-BTC with PECVD of perfluoroalkanes, the aging of materials under humid conditions, and the subsequent ammonia microbreakthrough experiments on milligram quantities of microporous materials. Cu-BTC has an extremely high surface area (~1,800 m2/g) when compared to most materials or surfaces that have been previously treated by PECVD methods. Parameters such as chamber pressure and treatment time are extremely important to ensure the perfluoroalkane plasma penetrates to and reacts with the inner MOF surfaces. Furthermore, the protocol for ammonia microbreakthrough experiments set forth here can be utilized for a variety of test gases and microporous materials.

Herein the procedures for plasma enhanced chemical vapor deposition of perfluoroalkanes on microporous materials such as metal-organic frameworks to enhance their stability and hydrophobicity are described. Furthermore, breakthrough testing of milligram quantities of samples is described in detail.

プラズマを介した疎水性有機金属フレームワークの製造は、アンモニアの除去のためにペルフルオロアルカンの化学的気相成長法を強化

Plasma enhanced chemical vapor deposition (PECVD) of perfluoroalkanes has long been studied for tuning the wetting properties of surfaces. For high ...

化学

Synthesis and Characterization of Functionalized Metal-organic Frameworks

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

Synthesis, activation, and characterization of intentionally designed metal-organic framework materials is challenging, especially when building blocks are incompatible or unwanted polymorphs are thermodynamically favored over desired forms. We describe how applications of solvent-assisted linker exchange, powder X-ray diffraction in capillaries and activation via supercritical CO2 drying, can address some of these challenges.

官能化有機金属構造体の合成とキャラクタリゼーション

Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and ...

Synthesis of a Water-soluble Metal&#8211;Organic Complex Array

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as Ru(II), Pt(II), and Rh(III). The compound, named as a water-soluble metal-organic complex array (WSMOCA), is obtained through 1) the conventional solution-chemistry-based preparation of the corresponding metal complex monomers having a 9-fluorenylmethyloxycarbonyl (Fmoc)-protected amino acid moiety and 2) their sequential coupling together with other water-soluble organic building units on the surface-functionalized polymeric resin by following the procedures originally developed for the solid-phase synthesis of polypeptides, with proper modifications. Traces of reactions determined by mass spectrometric analysis at the representative coupling steps in stage 2 confirm the selective construction of a predetermined sequence of metal centers along with the peptide backbone. The WSMOCA cleaved from the resin at the end of stage 2 has a certain level of solubility in aqueous media dependent on the pH value and/or salt content, which is useful for the purification of the compound.

Synthesis of a Water-soluble Metal&amp;#8211;Organic Complex Array

A potential general method for the synthesis of water-soluble multimetallic peptidic arrays containing a predetermined sequence of metal centers is presented.

水溶性有機金属錯体アレイの合成

We demonstrate a method for the synthesis of a water-soluble multimetallic peptidic array containing a predetermined sequence of metal centers such as ...

Synthesis of a Thiol Building Block for the Crystallization of a Semiconducting Gyroidal Metal-sulfur Framework

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and porous metal-dithiolene network in the highly ordered single crystalline state. Unlike the highly reactive free-standing thiols, which tend to decompose and complicate the crystallization of metal-thiolate open frameworks, the thioester reacts in situ to provide the thiol species, serving to mitigate the reaction between the mercaptan units and the metal centers, and to improve crystallization consequently. Specifically, the thioester was synthesized in a one-pot procedure: an aromatic bromide (hexabromotriphenylene) reacted with excess sodium thiomethoxide under vigorous conditions to first form the thioether intermediate product. The thioether was then demethylated by the excess thiomethoxide to provide the thiolate anion that was acylated to form the thioester product. The thioester was conveniently purified by standard column chromatography, and then used directly in the framework synthesis, wherein NaOH and ethylenediamine serve to revert in situ the thioester to the thiol linker for assembling the single-crystalline Pb(II)-dithiolene network. Compared with other methods for thiol synthesis (e.g., by cleaving alkyl thioether using sodium metal and liquid ammonia), the thioester synthesis here uses simple conditions and economical reagents. Moreover, the thioester product is stable and can be conveniently handled and stored. More importantly, in contrast to the generic difficulty in accessing crystalline metal-thiolate open frameworks, we demonstrate that using the thioester for in situ formation of the thiol linker greatly improves the crystallinity of the solid-state product. We intend to encourage broader research efforts on the technologically important metal-sulfur frameworks by disclosing the synthetic protocol for the thioester as well as the crystalline framework solid.

Here, we present a one-pot, transition-metal-free synthesis of thiols and thioesters from aromatic halides and sodium thiomethoxide, followed by the preparation of single crystals of a metal-dithiolene network using thiol species generated in situ from the more stable and tractable thioester.

半導体 Gyroidal 金属硫黄フレームワークの結晶化に対するチオール ビルディング ブロックの合成

We present a method for preparing thioester molecules as the masked form of the thiol linkers and their utilization for accessing a semiconducting and ...

Surface Functionalization of Metal-Organic Frameworks for Improved Moisture Resistance

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. However, the main issue limiting their applicability is their poor stability in humid conditions. The common methods to overcome this problem involve the formation of strong metal-linker bonds by using highly charged metals, which is limited to a number of structures, the introduction of alkylic groups to the framework by post-synthetic modification (PSM) or chemical vapour deposition (CVD) to enhance overall hydrophobicity of the framework. These last two usually provoke a drastic reduction of the porosity of the material. These strategies do not permit to exploit the properties of the MOF already available and it is imperative to find new methods to enhance the stability of MOFs in water while keeping their properties intact. Herein, we report a novel method to enhance the water stability of MOF crystals featuring Cu2(O2C)4&#160;paddle-wheel units, such as HKUST (where HKUST stands for Hong Kong University of Science &#38; Technology), with the catechols functionalized with alkyl and fluoro-alkyl chains. By taking advantage of the unsaturated metal sites and the catalytic catecholase-like activity of CuII ions, we are able to create robust hydrophobic coatings through the oxidation and subsequent polymerization of the catechol units on the surface of the crystals under anaerobic and water-free conditions without disrupting the underlying structure of the framework. This approach not only affords the material with improved water stability but also provides control over the function of the protective coating, which enables the development of functional coatings for the adsorption and separations of volatile organic compounds. We are confident that this approach could also be extended to other unstable MOFs featuring open metal sites.

Robust functional catechol coatings were produced in one step by direct reaction of the material known as HKUST with synthetic catechols under anaerobic conditions. The formation of homogeneous coatings surrounding the entire crystal is ascribed to the biomimetic catalytic activity of Cu(II) dimers on the external surface of the crystals.

金属有機性フレームワークの耐湿性を向上のための表面機能化

Metal-organic frameworks (MOFs) are a class of porous inorganic materials with promising properties in gas storage and separation, catalysis and sensing. ...

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids with adsorbates. Vibrational spectra provide information on the chemical nature of adsorbed species and their structure. Thus, they are very useful for obtaining molecular level understanding of surface species. The IR spectrum of the sample itself gives some direct information about the material. General conclusions can be drawn concerning hydroxyl groups, some stable surface species and impurities. However, the spectrum of the sample is &#34;blind&#34; with respect to the presence of coordinatively unsaturated ions and gives rather poor information about the acidity of surface hydroxyls, species decisive for the adsorption and catalytic properties of the materials. Furthermore, no discrimination between bulk and surface species can be made. These problems are solved by the use of probe molecules, substances that interact specifically with the surface; the alteration of some spectral features of these molecules as a result of adsorption provides valuable information about the nature, properties, location, concentration, etc., of the surface sites.
The experimental protocol for in-situ IR studies of gas/sample interaction includes preparation of a sample pellet, activation of the material, initial spectral characterization through the analysis of the background spectra, characterization by probe molecules, and study of the interaction with a particular set of gas mixtures. In this paper we investigate a zirconium terephthalate metal organic framework, Zr6O4(OH)4(BDC)6 (BDC = benzene-1,4-dicarboxylate), namely UiO-66 (UiO refers to University of Oslo). The acid sites of the UiO-66 sample are determined by using CO and CD3CN as molecular probes. Furthermore, we have demonstrated that CO2 is adsorbed on basic sites exposed on dehydroxylated UiO-66. Introduction of water to the system produces hydroxyl groups acting as additional CO2 adsorption sites. As a result, CO2 adsorption capacity of the sample is strongly enhanced.

In situ FTIR Spectroscopy as a Tool for Investigation of Gas/Solid Interaction: Water-Enhanced CO2 Adsorption in UiO-66 Metal-Organic Framework

The use of FTIR spectroscopy for investigation of the surface properties of polycrystalline solids is described. Preparation of sample pellets, activation procedures, characterization with probe molecules and model studies of CO2 adsorption are discussed.

イン・シチュガス・固体相互作用の調査ツールとしてのFTIR分光法:UiO-66金属有機フレームワークにおける水強化CO2吸着

In situ infrared spectroscopy is an inexpensive, highly sensitive, and selective valuable tool to investigate the interaction of polycrystalline solids ...

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks (MOFs)

Substrate size discrimination by the pore size and homogeneity of the chiral environment at the reaction sites are important issues in the validation of the reaction site in metal-organic framework (MOF)&#8211;based catalysts in an enantioselective catalytic reaction system. Therefore, a method of validating the reaction site of MOF-based catalysts is necessary to investigate this issue. Substrate size discrimination by pore size was accomplished by comparing the substrate size versus the reaction rate in two different types of carbonyl-ene reactions with two kinds of MOFs. The MOF catalysts were used to compare the performance of the two reaction types (Zn-mediated stoichiometric and Ti-catalyzed carbonyl-ene reactions) in two different media. Using the proposed method, it was observed that the entire MOF crystal participated in the reaction, and the interior of the crystal pore played an important role in exerting chiral control when the reaction was stoichiometric. Homogeneity of the chiral environment of MOF catalysts was established by the size control method for a particle used in the Zn-mediated stoichiometric reaction system. The protocol proposed for the catalytic reaction revealed that the reaction mainly occurred on the catalyst surface regardless of the substrate size, which reveals the actual reaction sites in MOF-based heterogeneous catalysts. This method for reaction site validation of MOF catalysts suggests various considerations for developing heterogeneous enantioselective MOF catalysts.

Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs

Here, we present a protocol for active site validation of metal-organic framework catalysts by comparing stoichiometric and catalytic carbonyl-ene reactions to find out whether a reaction takes place on the inner or outer surface of metal-organic frameworks.

キラル金属有機フレームワーク(MRF)を用いた不均一なエナンチオ選択的触媒の開発

Substrate size discrimination by the pore size and homogeneity of the chiral environment at the reaction sites are important issues in the validation of ...

Synthesis of Single-Crystalline Core-Shell Metal-Organic Frameworks

Because of their designability and unprecedented synergistic effects, core-shell metal-organic frameworks (MOFs) have been actively examined recently. However, the synthesis of single-crystalline core-shell MOFs is very challenging, and thus a limited number of examples have been reported. Here, we suggest a method of synthesizing single-crystalline HKUST-1@MOF-5 core-shells, which is HKUST-1 at the center of MOF-5. Through the computational algorithm, this pair of MOFs was predicted to have the matched lattice parameters and chemical connection points at the interface. To construct the core-shell structure, we prepared the octahedral- and cubic-shaped HKUST-1 crystals as a core MOF, in which the (111) and (001) facets were mainly exposed, respectively. Via the sequential reaction, the MOF-5 shell was well-grown on the exposed surface, showing a seamless connect interface, which resulted in the successful synthesis of single-crystalline HKUST-1@MOF-5. Their pure phase formation was proved by optical microscopic images and powder X-ray diffraction (PXRD) patterns. This method presents the potential of and insights into the single-crystalline core-shell synthesis with different kinds of MOFs.

Here, we demonstrate a protocol for the two-step synthesis of single-crystalline core-shells using a non-isostructural metal-organic framework (MOF) pair, HKUST-1 and MOF-5, which have well-matched crystal lattices.

単結晶コアシェル金属有機構造体の合成

Because of their designability and unprecedented synergistic effects, core-shell metal-organic frameworks (MOFs) have been actively examined recently. ...

A Technical Guide for Performing Spectroscopic Measurements on Metal-Organic Frameworks

Metal-organic frameworks (MOFs) offer a unique platform to understand light-driven processes in solid-state materials, given their high structural tunability. However, the progression of MOF-based photochemistry has been hindered by the difficulty in spectrally characterizing these materials. Given that MOFs are typically larger than 100 nm in size, they are prone to excessive light scatter, thereby rendering data from valuable analytical tools like transient absorption and emission spectroscopy nearly uninterpretable. To gain meaningful insights of MOF-based photo-chemical and physical processes, special consideration must be taken toward properly preparing MOFs for spectroscopic measurements, as well as the experimental setups that garner higher quality data. With these considerations in mind, the present guide provides a general approach and set of guidelines for the spectroscopic investigation of MOFs. The guide addresses the following key topics: (1) sample preparation methods, (2) spectroscopic techniques/measurements with MOFs, (3) experimental setups, (3) control experiments, and (4) post-run stability characterization. With appropriate sample preparation and experimental approaches, pioneering advancements toward the fundamental understanding of light-MOF interactions are significantly more attainable.

Here, we use a polymer stabilizer to prepare metal-organic framework (MOF) suspensions that exhibit markedly decreased scatter in their ground-state and transient absorption spectra. With these MOF suspensions, the protocol provides various guidelines to characterize the MOFs spectroscopically to yield interpretable data.

金属有機フレームワークの分光測定を行うための技術ガイド

Metal-organic frameworks (MOFs) offer a unique platform to understand light-driven processes in solid-state materials, given their high structural ...

酸化還元活性MOFの磁気特性評価:固体電気化学

Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs show outstanding performance in terms of gravimetric or areal capacitance and cyclic stability, unfortunately their electrochemical mechanisms are not well understood in most cases. Traditional spectroscopic techniques, such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS), have only provided vague and qualitative information about valence changes of certain elements, and the mechanisms proposed based on such information are often highly disputable. In this article, we report a series of standardized methods, including the fabrication of solid-state electrochemical cells, electrochemistry measurements, the disassembly of cells, the collection of MOF electrochemical intermediates, and physical measurements of the intermediates under the protection of inert gases. By using these methods for quantitatively clarifying the electronic and spin state evolution within a single electrochemical step of redox-active MOFs, one can provide clear insight into the nature of electrochemical energy storage mechanisms not only for MOFs, but also for all other materials with strongly correlated electronic structures.

著者スポットライト:酸化還元活性金属有機フレームワークの固体電気化学における中間体の磁気測定特性評価  

Ex situ magnetic surveys can directly provide bulk and local information on a magnetic electrode to reveal its charge storage mechanism step by step. Herein, electron spin resonance (ESR) and magnetic susceptibility are demonstrated to monitor the evaluation of paramagnetic species and their concentration in a redox-active metal-organic framework (MOF).

酸化還元活性金属-有機骨格の固体電気化学における中間体の磁気特性評価

Electrochemical energy storage has been a widely discussed application of redox-active metal-organic frameworks (MOFs) in the past 5 years. Although MOFs ...